1. Field
This disclosure is directed to radio frequency identification (RFID) tags using RFID circuits and antennas having unmatched frequency bands.
2. Description of the Related Art
RFID tags comprise RFID circuits and tag antennas. Each conventional RFID circuit is designed for use in a particular band of frequencies. For example, because of mandates of many large retail chain stores, RFID tags operating in the 860-960 Mega-Hertz (MHz) band of frequencies (and operating under a communication protocol promulgated by EPCglobal Inc.) are particularly prevalent. In some cases, the volume of RFID circuits operable in the mandated systems has pushed pricing for RFID circuits to five cents a piece or less, and thus correspondingly the RFID tags are relatively inexpensive.
However, the physical size of a tag antenna used on a RFID tag, and thus the physical size of the RFID tag itself, is function of the frequency of operation of the tag. In the 860-960 MHz band of frequencies, quarter-wave tag antennas are on the order of three to four inches, and thus RFID tags operating in this band have at least one dimension spanning three to four inches. In some situations, however, a RFID tag having a three to four inch dimension is too long for the underlying object. RFID tags may be made smaller by re-design of the RFID circuit and tag antenna for a new, higher operating frequencies, but such a design change is prohibitively expensive, especially where the volume of RFID tags to be produced is relatively small in comparison to the engineering costs associated with RFID circuit re-design efforts.